Valve arrangement having two valves in a common housing and use of the arrangement in a vapor generating and utilizing plant

ABSTRACT

The invention relates to a valve design wherein a smaller and a larger valve are placed in a common housing and arranged for independent operation, the smaller valve serving for regulating the flow of operating fluid therethrough and the larger valve affording full flow or no flow of operating medium therethrough. The invention also relates to the use of the valve arrangement in a steam or vapor generating plant for facilitating starting thereof.

D United States Patent 11 1 1111 3,734,134 Vogeli 1 May 22, 1973 [54] VALVE ARRANGEMENT HAVING [58] Field of Search ..137/599.2, 637.2

TWO VALVES IN A COMMON HOUSING AND USE OF THE R ferences Cited GENERATING AND UTILIZING PLANT 874,113 12/1907 Peck ..l37/599.2 X 1 lnvenmrl 8 wlesendangem Swlt- 2,010,194 8/1935 McNeelan et al. ..l37/637.2 zerland 2,659,384 11/1953 Lowe ..l37/599.2

[73] Ass1gnee: Sul zer Brothers, Ltd., Wmterthur, Primary Examiner Robert GNilson Switzerland Attorneyl(enyon et al. [22] Filed: Oct. 27, 1971 21 Appl. No.: 193,224 [57] ABSTRACT The invention relates to a valve design wherein a Related Apphcamm Data smaller and a larger valve are placed in a common [63] Continuation of Ser. No. 3,052, Jan. 15, 1970, abanhousing and arranged for independent Operation, the d i smaller valve serving for regulating the flow of operat ing fluid therethrough and the larger valve affording Foreign A licati P i it D t full flow or no flow of operating medium therethrough. The invention also relates to the use of Jan. 28, 1969 Switzerland ..001240/69 the valve arrangement in a steam or vapor generating plant for facilitating starting thereof. [52] US. Cl. ..l37/637.2, 137/5992, 251/14 [51] Int. Cl ..F16k 1/02 5 Claims, 2 Drawing Figures 37 33 i Q 1 i 22 3s 1 L 33 5 -54 28 PATENTEWYP-ZW 3,734,134

SHEET 1 [1F 2 i Inventor:

ERNST VOGEL.

VALVE ARRANGEMENT HAVING TWO VALVES IN A COMMON HOUSING AND USE OF THE ARRANGEMENT IN A VAPOR GENERATING AND UTILIZING PLANT This is a continuation of application Ser. No. 3,052 filed Jan. 15, 1970 now abandoned.

This invention relates to a valve arrangement comprising a first closing element which, in combination with a suitable seat, forms a first valve. The invention also relates to the combination of the valve arrangement according to the invention with a steam generating plant.

The valve arrangement according to the invention is characterized by the provision of a second closing element which, with a passage for an operating fluid in the aforesaid first closing element forms a second valve arranged in parallel relation with the first valve with respect to fluid flow, the second valve being adjustable independently of the first valve. The combination of a plurality of valves in a housing is known; in the conventional arrangements one of the valves functions as an auxiliary or regulating valve assisting the opening and closing movement of a second valve. These conventional valves do not have adjustable valve effects which are independent of one another.

An object of the invention is the use of the valve arrangement according to the invention in lieu of a conventional parallel arrangement of a regulating valve for great pressure drops, particularly critical pressure drops, and a separate stop valve having a greater flow area than that of said regulating valve.

The advantages of the valve arrangement according to the invention are the placement of two valves in a single housing, a smaller space requirement, and the simplification of the piping for the operating fluid in a plant equipped with the new valve arrangement since no by-pass line containing the smaller valve is required for the larger valves. The advantage of the use of the valve arrangement according to the invention in combination with a critical pressure steam or vapor generator will now be described. At a critical pressure drop of the operating fluid in a valve, the fluid attains the speed of sound whereby strong vibrations and/or cavitations may occur which destroy the valve. The smaller one of the two valves in a common casing may be built as a shut-off and regulating valve and very strong, i.e., suitable for great pressure drops, for regulating the flow of the operating fluid until the pressure at the valve has reached a value permitting opening the larger valve which is built for a considerably smaller, subcritical pressure drop. The smaller valve may be made as small as is possible considering the operating conditions of the plant wherein it is used. The larger valve has a large flow area and operates at little pressure drop. It may be constructed as an open closed or as a stop valve, eventually provided with course positioning means instead of with a continuously operating control drive.

The drawing accompanying the present application illustrates a preferred embodiment of the invention.

FIG. I is a longitudinal part-sectional view of a valve arrangement according to the invention;

FIG. 2 is a simplified, part-sectional layout of a forced-flow steam or vapor generating plant comprising a valve arrangement according to the invention.

Referring more particularly to FIG. 1 of the drawing, numeral 1 designates a housing having an inlet 2 and an outlet 3 for an operating fluid. A. first valve stem 6 is placed in a guide element 4 which also forms the closure of the valve housing 1 and is sealingly connected to the valve housing by means of an autoclave closure 5. The stem 6 extends through a stuffing box 7 and is connected to a threaded spindle by means of two disconnectable coupling elements 8 and 9. The spindle 10 is supported by a nut element which is supported by a support element 18 whereto the nut element 15 is connected by two ballbearings 16 and 17. Rotation of the spindle 10 is prevented by a forked guide lever 19 which is connected by a link 20 to eyes 21 attached to the support element 18.

An internally toothed gear 23 is wedged to an extension sleeve 22 of the nut element 15, a gear engaging the internal teeth 24 of the gear 23. The gear 25 is rigidly connected to an adjacent gear 27 by means of a pin 26, the gear 27 meshing with a stationary internal gear 28. The number of teeth of the gear 25 differs from that of the gear 27 by one. The gears .25 and 27 are placed on a pin 31 whose ends rest in flanges 32 and 33, respectively, of an annular support 34. There are four pins 31 with gears mounted thereon which are supported by the support 34 at 90 angular spacing. The upper flange 33 of the support 34 is provided with internal teeth 35 meshing with teeth of a pinion 36 of a servomotor 37 and with the teeth of a pinion, not shown, of a second servomotor 38.

The lower end of the first valve stem 6 has a closure body 40 connected thereto which, by means of a seat 41 provided in the valve housing 1, forms a first valve 42. The closure body 40 has an extension provided with openings 43, 44 and 45 affording passage of the operating fluid. The first valve stem 6 is provided with a longitudinal bore 46 wherein a second valve stem 47 is guided, the upper end of the second valve stem being guided in a stuffing box 48, the lower end 49 of the stem 47 being of increased diameter to snugly fit into the bore 46. The large diameter end of the second valve stem forms a closure body capable of sitting on a seat 50 in the opening 43 for forming a second valve 51. The second valve stem 47 is connected to a push rod 58 of a servomotor 59 having a linear operating stroke, by means of a releasable coupling 55, a spindle 56, and a releasable coupling 57. The stem 56 is vertically movable in the threaded spindle 10. The servomotor 59 is rigidly connected to the spindle 10. The servomotor 59 is provided with a handwheel 60 for manual operation of the push rod 58, if desired. Since the servomotor 59 is rigidly connected to the stationary threaded spindle 10, the second valve stem 47 can be moved independently of the first stem 6 so that the valve effects of the valves 42 and 51 are independent of one another. The two valves may have a common drive. In this case the position of one valve is dependent on the position of the second valve; the valve effects, however, of the two valves are separated.

The flow area of the first valve 42 is large and the pressure drop across this valve is small. It may be designed as a shut-off valve which is either open or closed. The second valve 51 has a much smaller flow area and may be designed as a shut-off and regulating valve. The second valve is built very strong and affords control of the rate of flow of operating fluid at a great pressure drop, for example a pressure drop which is equal to or greater than the critical pressure drop.

The use according to the invention of the aforedescribed valve arrangement in connection with starting a forced flow steam generator will now be described. Referring to FIG. 2 of the drawing, numeral .65 designates a feedpump, 66 a feedwater valve, 67 a feedwater heater, 68 an economizer heating surface 69 a circulating pump, 70 an evaporator, 71 the valve arrangement according to the invention comprising partial valves BT and BTB, 72 a superheater, 73 a turbine inlet valve, 74 a high pressure turbine, 75 a reheater, 76 a low pressure turbine, 77 a condenser, 78 a condensate pump, 79 a condensate preheater, 80 a feedwater container, 81 a water circulating pipe, 83 a liquid-vapor separator having a liquid space and a vapor space, 82 a pressure control valve in a pipe connecting the separator to a conduit 87 receiving vapor from the evaporator 70, 85 a pipe for removing liquid separated in the separator 83, 84 a valve in the pipe 85 and 86 a throttle valve in a conduit connecting the vapor space of the separator 83 to the conduit 87.

The purpose of the valve arrangement 71 which is in parallel relation to the separator 83, is to prevent flow of water from the evaporator 70 through the conduit 87 into the superheater 72, when the plant is started. In that case the valves BT, BTB and the valve 82 which is set for a predetermined pressure, for example 70 kglcm are initially closed. The turbine inlet valve 73 is partly open. When the pressure exceeds 70 kg/cm the valve 82 opens and operating fluid flows into the separator 83. The separated vapor or steam flows through the throttle valve 86 into the superheater 72. The steam superheated in the superheater 72 flows through the turbine inlet valve 73 into the high pressure turbine 74. The valve 82 is gradually adjusted, by means not shown, to maintain a gradually increased pressure until, after a predetermined temperature, for example 290 C, has been reached by the steam generated in the evaporator 70, a constant pressure, for example 245 kg/cm is maintained upstream of the valve 82. At further increase of the load on the steam generating plant operation of the separator 83 is discontinued by closing the valve 82 and the valve BTB is opened. This is permissible because the enthalpy at the outlet of the evaporator 70, in the meantime, becomes so great that, when the operating fluid whose pressure is super-critical at the valve BTB, is throttled, only steam or vapor is generated. The pressure of 245 kg/cm at the outlet of the steam generator or evaporator 70 is retained when changing operation from through the separator 83 to operation through the valve BTB. Combustion and feedwater supply are further increased and the output of the turbine is increased accordingly. For the time being the turbine inlet valve 73 remains in its initial position. When the valve BTB is opened, critical pressure drop occurs therein. On further opening of the valve BTB the pressure upstream of the turbine inletvalve 73 increases and the pressure drop across the valve BTB decreases. If the pressure drop across the valve is below the critical value, i.e., if the pressure upstream of the valve [is 245 kg/cm, the valve BT may be opened. When the plant operates at full load the valve ET is fully opened, whereas the valve BTB may remain open or may close dependent on the control arrangement. With respect to details of the starting operation of a forced-flow steam generating plant reference is made to U.S. Pat. No. 3,262,431.

What is claimed is:

1. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said first valve stem being secured against rotation, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem and drive means connected to said first valve and including a threaded portion on said first valve stem, a rotatably mounted nut element in meshing engagement with said threaded portion, said nut element having an internally toothed gear thereon, a first gear engaging said internally toothed gear, a second gear rigidly connected to said first gear and being in meshing engagement with a stationary internal gear having a number of teeth differing by at least one from that of the second gear, a support connected with said nut element rotatably mounting said first gear and said second gear on a common axis thereof, said support having an internally toothed gear and at least two servomotors provided with drive pinions meshing with said internally toothed gear.

2. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship to each other with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said first valve stem being secured against rotation, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem and drive means including a servomotor connected to said second valve stem for actuating said second valve independently of said first valve, said drive means being connected with said first valve stem of said first valve to move with said first valve stem during displacement of said first valve stem relative to said first valve seat and a second drive means including at least one servomotor for actuating said first valve.

3. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship to each other with respect to flow a fow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve 'stem being slidably mounted in said firstvalve stem, and drive means including a servomotor connected to said second valve stem for actuating said second valve independently of said first valve, said drive means being connected with said first valve stem of said first 'valve to move with said first valve stem during displacement of said first valve stem relative to said first valve seat and a second drive means including at least one servomotor for actuating said first valve.

4. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem and drive means connected to said first valve and including a threaded portion on said first valve stem, a rotatably mounted nut element in meshing engagement with said threaded portion, said nut element having an internally toothed gear thereon, a first gear engaging said internally toothed gear, a second gear rigidly connected to said first gear and being in meshing engagement with a stationary internal gear having a number of teeth differing by one from that of the second gear, a support connected with said not element rotatably mounting said first gear and said second gear on a common axis thereof, said support having an internally toothed gear and at least two servomotors provided with drive pinions meshing with said internally toothed gear.

5. A valve system comprising a coaxial arrangement with drive pinions meshing with said toothed gear.

Patent No. 3a73 b 3 Dated Ma 22 197 Ernst Vogeli Inventor(s) It is certified that errdr appears in the abpve-identified patent and that said Letters Patent are hereby corrected as shown below:

Column -1, line 4 delete "to flow a few" and insert --to a. flow.

Signed and sealed this 27th day of November 1973.

(SEAL) Attest:

EDWARD M.PLET CHER,JR. RENE D. TEGTMEYER Attesting Officer Acting Commissionerof Patents F can PO-1 050 1 0-69) uscpMM-oc scam-ps9 u.s GOVERNMENT gmn rl'us OFFICE: lg 0-36-35 5.v 

1. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said first valve stem being secured against rotation, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem and drive means connected to said first valve and including a threaded portion on said first valve stem, a rotatably mounted nut element in meshing engagement with said threaded portion, said nut element having an internally toothed gear thereon, a first gear engaging said internally toothed gear, a second gear rigidly connected to said first gear and being in meshing engagement with a stationary internal gear having a number of teeth differing by at least one from that of the second gear, a support connected with said nut element rotatably mounting said first gear and said second gear on a common axis thereof, said support having an internally toothed gear and at least two servomotors provided with drive pinions meshing with said internally toothed gear.
 2. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship to each other with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said first valve stem being secured against rotation, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem and drive means including a servomotor connected to said second valve stem for actuating said second valve independently of said first valve, said drive means being connected with said first valve stem of said first valve to move with said first valve stem during displacement of said first valve stem relative to said first valve seat and a second drive means including at least one servomotor for actuating said first valve.
 3. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship to each other with respect to flow a fow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem, and drive means including a servomotor connected to said second valve stem for actuating said second valve independently of said first valve, said drive means being connected with said first valve stem of said first valve to move with said first valve stem during displacement of said first valve stem relative to said first valve seat and a second drive means including at least one servomotor for actuating said first valve.
 4. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem and drive means connected to said first valve and including a threaded portion on said first valve stem, a rotatably mounted nut element in meshing engagement with said threaded portion, said nut element having an internally toothed gear thereon, a first gear engaging said internally toothed gear, a second gear rigidly connected to said first gear and being in meshing engagement with a stationary internal gear having a number of teeth differing by one from that of the second gear, a support connected with said nut element rotatably mounting said first gear and said second gear on a common axis thereof, said support having an internally toothed gear and at least two servomotors provided with drive pinions meshing with said internally toothed gear.
 5. A valve system comprising a coaxial arrangement of a first valve and a second valve in parallel relationship with respect to a flow of fluid therethrough, said first valve comprising a first valve stem having a first closure body thereon and a first valve seat, said second valve comprising a second valve stem and a second valve seat on said first closure body, said second valve stem being slidably mounted in said first valve stem, and drive means connected to said first valve for driving said first valve, said drive means comprising a toothed gear and at least two servomotors provided with drive pinions meshing with said toothed gear. 